1. Field of the Invention
The present invention relates to a suturing instrument used for performing suture and/or ligature with a suture in a surgical operation while the interior of a body cavity is observed with an endoscope.
2. Description of the Related Art
In recent years, a surgical operation is often performed while observing the interior of the body cavity with an endoscope. When a special instrument must be operated within a body cavity, where movement of the instrument is limited, while observing a planar image sent from an endoscope with a monitor in this manner, it is very difficult to perform suture or ligature with a suture. For this reason, many instruments and methods are developed for performing ligation easily.
Transfixion suture methods that are currently generally performed are divided into an external ligation method and an internal ligation method. According to external ligation method, a suture is passed through a living body tissue in a body cavity. The two ends of the suture are extracted outside the body. A loose knot is formed on the suture outside the body. Then, this knot is fed into the body with a special instrument or the like that feeds the knot into the body.
U.S. Pat. No. 5,144,961 describes an instrument which ligates a suture in accordance with a method similar to that described above. According to this instrument, one end of a needle (end portion on a side to be remote from the needle) attached with a suture is wound on a hollow rod in advance, and a knot is formed on the hollow rod. Only a portion of the suture not wound on the rod and the needle are inserted into the body cavity. After suture, the suture is extracted outside the body. The suture is inserted through the inner hole of the hollow rod. The knot is removed from the rod, and the hollow rod is pushed in, thereby feeding the knot into the body cavity.
When the internal method is to be performed, square knot formation, or triple knot formation is performed by using two forceps for a laparoscopic operation in the same manner as in an ordinary abdominal operation. This ligation will be described later in detail.
A method of simplifying the operation of forming a knot in the body is disclosed in, e.g., U.S. Pat. No. 5,234,445. According to this method, a substantially lasso-like loop and a knot are formed midway along a suture attached with a needle, and the trailing portion of the suture following the loop and knot is passed through a hollow rod.
In this case, the knot is not located in the rod. The rod is inserted into the body cavity, the loop and the needle-attached suture attached to the distal end of the rod are inserted in the body cavity, and the target tissue is sutured while holding the needle with another forceps. Then, after the forceps is passed through the loop, the needle-side portion of the suture is held, and the needle-side portion of the suture is pulled to pass through the loop. Simultaneously, the hollow rod is pushed to feed the knot. Thus, the substantially lasso-like loop is closed, thereby forming a knot.
According to the method of performing ligation by using the two forceps in the body cavity, for example, the instruments to be used are forceps for a laparoscopic operation. Two forceps of this type are operated to perform square knot formation or triple knot formation as in an ordinary abdominal operation as described above.
According to an example of the procedure of above ligation, one end of the suture is picked up by the first forceps, and the suture is wound on the circumferential portion of the second forceps. Subsequently, the first forceps holding the one end of the suture is maintained in the suture-holding state, and the other end of the suture is gripped by the second forceps on which the suture is wound.
The first forceps is moved toward the distal end of the second forceps to bring the ring of the wound suture above the other end of the suture over the second forceps. In this state, the first and second forceps are pulled in the opposite directions to close the ring of the wound suture, thereby forming a knot.
Square knot formation or triple knot formation can be performed by repeating the above operation twice or three times while reversing the winding direction each time. When square knot formation is performed, a knot as shown in FIG. 5B can be obtained.
The knot obtained in this manner is stiff and firm. The suture can be reliably fastened by pulling the two ends of the suture with the two forceps horizontally in the opposite directions with respect to the knot as the center. The fastening degree and the like can be easily adjusted by forming a knot in this manner.
According to the conventional methods, however, when a knot is to be formed outside the body, since the two ends of the suture guided into the body must be extracted outside the body, the forceps must be inserted into and extracted from the body many times, leading to a cumbersome operation.
Since the two ends of the suture are extracted outside the body, the suture must be very long. Then, when the suture is pulled outside the body, the living body tissue through which the suture extends can be rubbed with the suture for a long period of time. Furthermore, a special instrument is required for feeding the knot into the body, leading to an increase in cost. Moreover, in the method of feeding an external knot into the body, it is sometimes difficult to firmly fasten the knot.
Since ligation performed in the body by using two forceps for a laparoscopic operation must be performed under a specific circumstance as described above, it is very difficult to operate the forceps as in an ordinary abdominal operation. In particular, it is difficult to wind the suture on the forceps, thus requiring techniques and skills.
In the method of forming a knot by fastening the other end of a suture with the substantially lasso-like loop, since the knot is comparatively loose, it may be untied. When, e.g., a substantially lasso-like loop is attached to the distal end of a rod and the rod is inserted into the body cavity, in addition to formation of two holes that must be formed in the patient's body surface to allow insertion of two forceps that perform ordinary suture, another hole must be formed in the patient's body surface to allow insertion of the rod, thereby increasing load to the patient.